segfault in apt-esm-hook

According to build log, apt-esm-hook seems to be in fact apt-hook/hook.cc at src package level:

install -D -m 755 hook /<<PKGBUILDDIR>>/debian/ubuntu-advantage-tools/usr/lib/ubuntu-advantage/apt-esm-hook

As Grant(https://code.launchpad.net/~orndorffgrant) mentioned in internal channels.

This likely could be related to the same Focal and later errors we are now seeing https://errors.ubuntu.com/problem/4166288511f42a64aee694b80c7d9d3103bb8581

We think the issue might be due to the apt origin of some configured repository not being present yet, or somehow properly configured.

To confirm, can we get the customer to provide us with:
  1. A gdb backtrace from running:
/usr/lib/ubuntu-advantage/apt-esm-hook process-templates

  2. Please also attach `apt-cache policy` output

  3. Maybe it's worth running this attached binary (test-apt-esm-hook) which has the following patch applied to our apt-esm-hook
Upstream source here: https://github.com/canonical/ubuntu-advantage-client/blob/main/apt-hook/hook.cc#L154

diff --git a/apt-hook/hook.cc b/apt-hook/hook.cc
index aed341d5..80b60c5d 100644
--- a/apt-hook/hook.cc
+++ b/apt-hook/hook.cc
@@ -151,7 +151,7 @@ static void check_esm_upgrade(pkgCache::PkgIterator pkg, pkgPolicy *policy, resu
    {
       for (pkgCache::VerFileIterator pf = ver.FileList(); !pf.end(); pf++)
       {
- if (pf.File().Archive() != 0 && pf.File().Origin() == std::string("UbuntuESM"))
+ if (pf.File().Archive() != 0 && DeNull(pf.File().Origin()) == std::string("UbuntuESM"))
          {
             if (std::find(res.esm_i_packages.begin(), res.esm_i_packages.end(), pkg.Name()) == res.esm_i_packages.end()) {
                 res.esm_i_packages.push_back(pkg.Name());
@@ -167,7 +167,7 @@ static void check_esm_upgrade(pkgCache::PkgIterator pkg, pkgPolicy *policy, resu
                 }
             }
          }
- if (pf.File().Archive() != 0 && pf.File().Origin() == std::string("UbuntuESMApps"))
+ if (pf.File().Archive() != 0 && DeNull(pf.File().Origin()) == std::string("UbuntuESMApps"))
          {
             if (std::find(res.esm_a_packages.begin(), res.esm_a_packages.end(), pkg.Name()) == res.esm_a_packages.end()) {
                 res.esm_a_packages.push_back(pkg.Name());

Put the related PR up as we explore this issue:
https://github.com/canonical/ubuntu-advantage-client/pull/1646

0051a8c41c4f19e5a569a88d8f9a9087 test-apt-esm-hook
Bionic build of apt-esm-hook with changeset from PR https://github.com/canonical/ubuntu-advantage-client/pull/1646

Please run on the affected system with `/test-apt-esm-hook process-templates` to confirm whether traceback is avoided.

Please mark this bug back to "New" when we have further actionable comments or information that needs re-review. Again thanks for the bug and details.

Thanks Chad, will do.

Update from UA customer:

"
thanks for the updates.
I confirm that "test-apt-esm-hook" runs successfully with no segfault. Looks like you found it!
"

Thank you for the confirmation of the fix!

We have landed an upstream commit in the project here
https://github.com/canonical/ubuntu-advantage-client/commit/264cb50838dd2abd1fe5418218283c1781f20f3b
as part of the pull request:
 - https://github.com/canonical/ubuntu-advantage-client/pull/1646

Our plan is to upload this fix to the Ubuntu development release (impish) as version 27.1 early next week.

Expect to see an upload of 27.1 to ppa:ua-client/staging when we begin testing that release.
We will perform a StableReleaseUpdate version 27.1 into Xenial, Bionic, Focal, Groovy and Hirsute once the upload Impish is accepted expect this within the next ~10 days in Bionic if all goes well.

Staging PPA for reference: https://launchpad.net/~ua-client/+archive/ubuntu/staging. We upload there first for testing before publishing bits.

As an FYI.

https://wiki.debian.org/DebianRepository/Format#Origin

"
Origin
Optional field indicating the origin of the repository, a single line of free form text.
"

This bug was fixed in the package ubuntu-advantage-tools - 27.1~21.10.1

---------------
ubuntu-advantage-tools (27.1~21.10.1) impish; urgency=medium

  * d/control:
    - specify debianutils min version
  * d/changelog:
    - fix lintian typos amend and redact incorrect 27.0 entry (GH: #1624)
  * lintian:
    - override ubuntu-advantage-pro wanted-by-target cloud-init
    - override xenial specific errors
    - rename package-specific overrides for pro vs tools
  * New upstream release 27.1:
    - apt-hook:
      + avoid segfault when comparing null Apt file origin to esm
        (LP: #1929123)
      + avoid wrapping static message formats at 80 chars
      + update go build flags based on lintian warnings (GH: #1626)
      + only add newlines for MOTD if message file length is non-zero
    - attach: do not print contract name if empty
    - autocomplete: Do not show beta services in autocomplete (GH: #1594)
    - cis:
      + make service non-beta
      + post enable message pointing to docs
      + update cis help url
    - docs: update releases.md per SRU review feedback on branch structuring
    - enable: correct messaging for beta service (GH: #1588)
    - errors: print a more helpful message when ssl fails (GH: #1618)
    - fips:
      + Block enabling fips if fips-updates once enabled (GH: #1600)
      + Update output of fips commands (GH: #1631)
    - livepatch: alert when snapd does not have wait cmd (LP: #1927329)
    - logging: remove tracebacks for UserFacingErrors (GH: #1586)
    - messaging:
      + Infra and Apps messaging is mutually exclusive (GH: #1573)
      + point to u.com/16-04 instead of u.com/advantage on ESM (GH: #1584)
      + separate _remove_msg_template. emit no warranty on infra disabled
    - pro: obtain AWS IMDSv2 API token before trying to grab pkcs7 doc
      (GH: #1608)
    - status: do not show info if not on contract (GH: #1592)
    - tests:
      + drop trusty specific tests
      + fix mock for handle_message_operations
      + fix motd message for bionic (GH: #1615)
      + integration tests for hirsute and groovy
      + manual test for trusty upgrade to xenial
      + reboot after dist-upgrade for upgrade test
      + test enabling CIS on focal (GH: #1582)
      + update messages in integration tests (GH: #1635)
      + use proposed pocket on xenial upgrade test
    - jenkins:
      + add pytest runs for xenial and bionic
      + run focal lxd integration tests

 -- Grant Orndorff <email address hidden> Mon, 24 May 2021 14:50:47 -0400

This bug was fixed in the package ubuntu-advantage-tools - 27.1~21.04.1

---------------
ubuntu-advantage-tools (27.1~21.04.1) hirsute; urgency=medium

  * Backport new upstream release: (LP: #1929597) to hirsute

 -- Lucas Moura <email address hidden> Thu, 27 May 2021 16:12:08 -0300

This bug was fixed in the package ubuntu-advantage-tools - 27.1~20.10.1

---------------
ubuntu-advantage-tools (27.1~20.10.1) groovy; urgency=medium

  * Backport new upstream release: (LP: #1929597) to groovy

 -- Lucas Moura <email address hidden> Thu, 27 May 2021 16:05:18 -0300

This bug was fixed in the package ubuntu-advantage-tools - 27.1~20.04.1

---------------
ubuntu-advantage-tools (27.1~20.04.1) focal; urgency=medium

  * Backport new upstream release: (LP: #1929597) to focal

 -- Lucas Moura <email address hidden> Thu, 27 May 2021 15:58:37 -0300

This bug was fixed in the package ubuntu-advantage-tools - 27.1~18.04.1

---------------
ubuntu-advantage-tools (27.1~18.04.1) bionic; urgency=medium

  * Backport new upstream release: (LP: #1929597) to bionic

 -- Lucas Moura <email address hidden> Thu, 27 May 2021 15:50:28 -0300